The present invention relates to a frame for bicycles or motorcycles, made of steel or light alloy. This frame differs from known frames in design, geometry and architecture and especially in that it takes advantage of the weight forces transforming them into dynamic moments. The invention is applicable to both the mechanical industry, in the manufacture of steel frames, and in the specialized cycle industry, using light alloys.
The invention is the fruit of studies in physics and mathematics, especially statics and dynamics. The frame exploits the law of gravitation of a body and the second principle of dynamics by which a force applied to a body which is free to move will produce an acceleration of said body. The frame also enables a rider to take up a better anatomical position.
Bodies in space are subject to the law of gravitation. A force having a distance from a stated point, in the case of a bicycle the hubs, creates a moment. The frame of the invention exploits the two above-described concepts, since the pushing moments, pushing forward and helping motion, are increased by raising the intensity of the applied forces, or by increasing the distances of the straight-line action of the forces from the stated point, also called the pole of the moment. The rider's weight rests partly on the handlebar (P2) and partly on the saddle (P1). The frame weight, the motor weight and the weight of all other parts forming the vehicle, indicated with (P4) rest throughout the frame partly on the point indicated with (4). The force originating from the thrust on the pedals also rests on the same points (3) and (4). Poin (3), where the head and the top tube meet, is a crossing point. Every weight force creates a reaction, which is equivalent and opposite (RA) and (RB) on the supports (1) and (2). Therefore this frame must have a point (3) at which the axis of the top tube (14) and the axis of the head tube (7) meet, at which all forces (P2) (.apprxeq.1/2P3), (.apprxeq.1/2P4) apply, and a point (4) at which the top tube (14) and the rear forks (9) meet, at which all forces (Plcos(w)) (.apprxeq.1/2MP3) (.apprxeq.1/2MP4) apply, respectively at a distance (S) and (T), in advance of the motion direction from the perpendiculars to the ground (A) and (B) passing through the hub (1) of the front wheel and the hub (2) of the rear wheel.
The direction of the weight forces, directed towards the ground and applied at point (3) for the front part, following the direction of the head tube (7) and the front forks (8) has to pass at a distance (S1) forward of the direction of motion from the hub (1) of the front steering wheel. The direction of the weight forces applied on point (4) for the rear part, following the rear forks (9) has to pass at distance (T1) in front of the hub (2) of the rear wheel. Distance (S1) must be equal or greater than distance (S), while distance (T1) can vary from point (2) to point (13) to avoid a forward overturn. The forward push increases with distances (S2), (S3) and (T2). If the distance is (T2) the rear fork (9) becomes the fork indicated by (31) and the weight force (P1) becomes the force indicated by (P1V). In frames having curved front forks (19), (29), the distances are calculated at the meeting point of the tangents at the angles, as shown in FIG. 1 and denoted by (21) and (30). The forces applied on point (3) are summed and become a force denoted by (F1), which force multiplied by distance (S1) creates the forward-pushing rotary moment (+2MS). The forces applied on point (4) add together to create a force indicated by (F2), which, multiplied by distance (T1) creates the rotary moment (+1MS). A rider's weight on the saddle (P1) is divided in accordance at angle (W) into force (Plcos(w)), which is perpendicular to the ground and the force Pisin (w) which has the same direction as the axis of the top tube (14). Force Plsin(w) at distance (17) form along its direction the force denoted by (F3), creating the pushing moment (+3MS). Force (F3) added to force (F1) creates a forwardly-directed resultant (R1), which still further increases the forward motion. In this way the frame can sum up all the forward-pushing moments having their pole in the hub (1) of the front wheel and in hub (2) of the rear wheel, due to the law of gravitation of bodies, summing up also the tangential forces (Y) developed on the wheels. This concept considers ground friction and air friction (X) as vehicle stabilizing forces.
More advantages can be obtained by changing the diameter of the front wheel and the rear wheel, by changing the shape and the geometry of the front and rear forks as shown in the drawing and indicated by (18), (19), (24), (25), (26), (27), (29), (31), or by a total or partial elimination of the frames parts indicated by (10), (11), (12), (28).
Known frames only partially or not at all transform the weight of the rider, of the frame itself, of the engine if there is one, of all other parts which form the vehicle, of the thrust of the pedals into kinetic energy. Certainly prior art frames are not based on this concept. Indeed, the direction of the rotary moment, which helps the forward push, produced by all the forces applied on the rear wheel (+1MS) is opposed to the direction of the rotary moments pushing backward on the front wheel (-2MS). This occurs because in such frames the weight forces application points (3) and (4) and the points (5) and (6) which denote the direction of forces (F1) and (F2) are between both perpendiculars to the ground (A) and (B) passing through the hubs (1) of the front wheel and (2) of the rear wheel. The concept of this invention is not even considered and exploited when the application point (3) lies behind the perpendicular to the ground (A) and the point (5) lies in front of the same perpendicular, or vice versa, inasmuch as this situation creates a backward pushing moment (-2MS); this occurs in the frames of U.S. Pat. No. 4,995,627 (Yun), Feb. 26, 1991, French patent 1,439,508 (Cesare Rizzato & C.S.N.C), Apr. 12, 1966, and Dutch patent 72,350 (Gra-Vemeijer et al.) May 15, 1953. The frame of Japanese patent publication 03 057 789 (Kimihiro Tsuchie) Mar. 13, 1991, (cf. Patent Abstracts of Japan, vol. 15 no. 212 (M-1118) May 30, 1991) has points (3) and (5) in front of the perpendicular (A) but has the direction of the forces (F1) following the front forks, which are turned backwards of an angle alpha; for this reason this frame cannot exploit the forward pushing moments and is suitable only for small bicycles, even though the fork rake is not traditional and the trail not well defined. French Patent 890,247 (Doderer), Feb. 2, 1944, is similar in the physical principle to Japanese patent 03 057 789 and therefore is not very manageable to ride, not based on the forward pushing moments concept and differs from the present invention also because this bicycle needs a turning arm and a fixed point to steer, on which the frame rests, indicated by (63) and (64) in figures (1) and (2). It also differs because, by steering, the hubs exit from the longitudinal axis, as shown in figure (5). In figures (3) and (4) of the same patent it clearly emerges that this patent is not based on rotary pushing moments and its only object is to increase the fork and the trail.